Add configuration file for default values to populate e.g. status choices for different core applications

[claire-peters]

I originally floated the idea of adding a new config file that would serve as a central reference list for all objects that are to be automatically added to the database in functions like add_allocation_defaults here. This PR is a follow-up on that. I included the default values for all apps with add_default commands in the config file, and then replaced the lists/tuples of those default values in the add_defaults commands with references to the config file.

There are a few ways I could see this config file being useful for other purposes, e.g., checking whether a given item is in the database in a given view.